/// @tags:
#include <algorithm>
#include <cctype>
#include <cstdio>
#include <cstring>
#include <queue>

template <typename T>
inline T &read(T &x) {
  x = 0;
  bool f = false;
  short ch = getchar();
  while (!isdigit(ch)) {
    if (ch == '-') f = true;
    ch = getchar();
  }
  while (isdigit(ch)) x = (x << 1) + (x << 3) + (ch ^ '0'), ch = getchar();
  if (f) x = -x;
  return x;
}

const int N = 3e3 + 5;

int dis[N][N];
int x[N], y[N];
int row, line, n;
std::queue<int> q;
bool vis[N];

int getdis(int x1, int y1, int x2, int y2) {
  return (x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2);
}

inline bool connected(int d, double r) { return r * r * 4 > d; }

inline bool check(double r) {
  memset(vis, 0, sizeof(vis));
  while (!q.empty()) q.pop();
  for (int i = 1; i <= n; i++)
    if (x[i] < r || row - y[i] < r) q.push(i), vis[i] = true;
  while (!q.empty()) {
    int u = q.front();
    q.pop();
    if (line - x[u] < r || y[u] < r) return false;
    for (int i = 1; i <= n; i++)
      if (!vis[i] && connected(dis[u][i], r)) vis[i] = true, q.push(i);
  }
  return true;
}

int main() {
#ifndef ONLINE_JUDGE
#ifdef LOCAL
  freopen64("/tmp/CodeTmp/testdata.in", "r", stdin);
  freopen64("/tmp/CodeTmp/testdata.out", "w", stdout);
#else
  freopen("P2498 [SDOI2012]拯救小云公主.in", "r", stdin);
  freopen("P2498 [SDOI2012]拯救小云公主.out", "w", stdout);
#endif
#endif

  read(n), --read(line), --read(row);
  for (int i = 1; i <= n; i++) --read(x[i]), --read(y[i]);
  for (int i = 1; i <= n; i++)
    for (int j = 1; j < i; j++)
      dis[i][j] = dis[j][i] = getdis(x[i], y[i], x[j], y[j]);
  double l = 0, r = std::min(row, line), mid;
  while (r - l > 1e-3) {
    mid = (l + r) / 2;
    if (check(mid)) l = mid;
    else
      r = mid;
  }
  printf("%.2lf\n", l);
  return 0;
}